Health hazard evaluation report: HETA-2002-0184-2888, Aero-Classics, Ltd., Huron, Ohio.
In March 2002 the National Institute for Occupational Safety and Health (NIOSH) received a health hazard evaluation (HHE) request from the management of Aero-Classics, Ltd., Huron, Ohio, a small company producing aluminum oil coolers used by the U.S. Army in the Abrams main battle tank. The request described employee health effects during the welding of aluminum oil coolers, including burning eyes, sore throats, headaches, sinus problems, and exhaustion. A site evaluation was conducted on April 29, 2002, which included a walk-through of the areas of concern and personal breathing-zone and area air sampling for a variety of potential contaminants, including metals (in this instance aluminum), ozone, and volatile organic compounds from a nearby vapor degreaser. The most significant exposures measured during this evaluation were to ozone, ranging up to 0.7 parts per million (ppm) for short-term (5 minute) exposures, measured in the general vicinity of the welders. These short-term concentrations exceeded the NIOSH Ceiling Limit for ozone of 0.1 ppm. Although full-shift sampling for ozone was not performed during this investigation, these concentrations suggest that the OSHA Permissible Exposure Limit (PEL) of 0.1 ppm for an 8-hour time-weighted average (TWA) may also be exceeded if welding is performed throughout a workday. Results of the remaining air samples were well below any pertinent occupational exposure criteria on the day of this survey. Of the 27 different minerals and metals sampled, only aluminum was detected in concentrations above trace levels. Similarly, workers in and near the welding room were exposed to very low (or non-detectable) concentrations of total particulate, solvents (trichloroethylene, the organic solvent used to clean the parts prior to assembly), hydrogen fluoride, hydrogen chloride, aldehydes, and phosgene. The brownish-red residue which accumulated on the visors worn by the welders contained trace amounts of iron and copper. This NIOSH investigator found that a health hazard existed to the welders from the high concentrations of ozone generated during tungsten inert gas (TIG) and metal inert gas (MIG) welding of the aluminum oil cooler components. Recommendations were made to reduce ozone exposures to the welders through the use of engineering controls (addition of more local exhaust ventilation, the use of larger exhaust hoods, and the addition of more general room ventilation for the welding area) and administrative controls (limiting the amount of welding performed during a workday). A recommendation was also made to provide respiratory protection from ozone while these engineering or administrative controls were implemented.